Synopsis: Granular Flow of a Melting Avalanche

Motion in an ice avalanche is strongly affected by the feedback effect of melting.
Synopsis figure
Daniel Ucko

In September 2002, one hundred million cubic meters of rock and ice separated from the northern slope of the Kazbek massif in North Ossetia, Russia. Traveling at times at nearly 300 km/hour, the resultant avalanche killed dozens of people and caused widespread damage. Ice avalanches from collapsing glaciers are not common in populated areas, but that may change as global temperatures rise. The Ossetia avalanche alerted researchers to the urgency of gaining a better understanding of the processes that control such flows.

In a paper in Physical Review Letters, Barbara Turnbull at the University of Nottingham, UK, tells us how she measured the significant effect of melting on the behavior of ice flows, which therefore differ from dry granular shear flows. In a series of four seemingly simple yet carefully controlled experiments, the author recorded high-speed video of the motion of ice particles that partially fill a slowly rotating narrow drum. The observations appear to confirm that lubrication and capillary action resulting from melting and wetting provide a positive feedback to granular ice flow, like avalanches. Interfacial melting increases flow velocity, which in turn speeds up the melting. However, the real achievement of the reported experiments is that researchers now have a controlled setup with which to study an urgent real-world scenario that has always been difficult to measure. – Sami Mitra


Features

More Features »

Subject Areas

Nonlinear DynamicsSoft MatterInterdisciplinary Physics

Previous Synopsis

Atomic and Molecular Physics

First Out of the Gate

Read More »

Next Synopsis

Atomic and Molecular Physics

Laser Cooling Tuned to the UV

Read More »

Related Articles

Focus: Why Soft Solids Get Softer
Mechanics

Focus: Why Soft Solids Get Softer

Soft materials like gels and creams exhibit fatigue resulting from the stretching of their constituent fibers, according to experiments and simulations. Read More »

Focus: <i>Video</i>—Roach-like Robots Act Collectively
Soft Matter

Focus: Video—Roach-like Robots Act Collectively

A collection of simple, self-propelled robots in a flexible and mobile corral can pull the whole group through a narrow space between walls. Read More »

Synopsis: The Geometry of Arctic Ponds
Geophysics

Synopsis: The Geometry of Arctic Ponds

A geometric model of meltwater ponds may help predict how the polar ice caps might evolve under future climate changes. Read More »

More Articles